Methods and apparatuses for creating code mapping functions for encoding an HDR image, and methods and apparatuses for use of such encoded images
First Claim
1. An encoding method, comprising the acts of:
- inputting pixel colors of an input high dynamic range video image, wherein the pixel colors have information of a luminance and a chromaticity;
applying an inverse of a mapping function, to derive a luma code (v) of the luminance of a pixel color, which mapping function is predetermined as comprising a first partial function which is defined as
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Abstract
To enable better encoding of the currently starting to appear high dynamic range images for use in full high dynamic range technical systems (containing an HDR display, and e.g. in an HDR grading application of a HDR movie), we invented a method of encoding a high dynamic range image, comprising the steps of: —inputting pixel colors of an input high dynamic range image, wherein the pixel colors have information of a luminance and a chromaticity; —applying an inverse of a mapping function to derive a luma code (v) of the luminance of a pixel color, which mapping function is predetermined as comprising a first partial function which is defined as (I), in which rho is a tuning constant, and v is the luma code corresponding to a luminance to be encoded, and a second partial mapping defined as L=LmPγ in which Lm is a peak luminance of a predefined reference display, and gamma is a constant which is preferably equal to 2.4, —outputting a matrix of pixels having a color encoding comprising the luma codes.
8 Citations
18 Claims
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1. An encoding method, comprising the acts of:
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inputting pixel colors of an input high dynamic range video image, wherein the pixel colors have information of a luminance and a chromaticity; applying an inverse of a mapping function, to derive a luma code (v) of the luminance of a pixel color, which mapping function is predetermined as comprising a first partial function which is defined as - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 13, 14)
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9. A video encoding apparatus, comprising:
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an input for obtaining pixel colors of an input high dynamic range video image, wherein the pixel colors have information of a luminance and a chromaticity; a grading managing unit arranged for applying an inverse of a mapping function to derive a luma code (v) of the luminance of a pixel color, which mapping function is predetermined as comprising a first partial function which is defined as - View Dependent Claims (10, 11, 12, 15, 16, 17)
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18. A method of video decoding, comprising:
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receiving an encoded high dynamic range video of images (S_im) and deriving therefrom an image encoding (Im_1) to be processed, and color mapping by applying a color mapping strategy to derive from the image encoding (Im_1) a high dynamic range image (REC_HDR), wherein the color mapping unit is arranged to apply on pixel lumas v in the image encoding (Im_1) a predetermined mapping function defined as comprising a first partial function which is
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Specification